Actin depolymerizing factor controls actin turnover and gliding motility in Toxoplasma gondii.

Area of Science:

• Parasitology
• Cell Biology
• Molecular Biology

Background:

• Apicomplexan parasites utilize actin-based motility for host cell invasion and dissemination.
• Actin dynamics are critical for parasite movement, yet most actin remains nonfilamentous in resting parasites.
• The role of actin-binding proteins in regulating parasite actin dynamics has been unclear.

Purpose of the Study:

• To investigate the in vivo function of Toxoplasma gondii actin depolymerizing factor (TgADF) in regulating actin dynamics and parasite behavior.
• To determine the necessity of TgADF for parasite motility, host cell invasion, and egress.

Main Methods:

• Conditional knockout strategy to suppress TgADF expression in Toxoplasma gondii.
• Immunofluorescence and electron microscopy to visualize actin structures.
• Analysis of parasite motility, gliding patterns, and host cell invasion/egress efficiency.

Main Results:

• Suppression of TgADF resulted in the accumulation of actin-rich filaments.
• TgADF-deficient parasites exhibited reduced motility speed, aberrant motion, and impaired gliding.
• Lack of TgADF severely compromised parasite entry and exit from host cells, blocking infection.

Conclusions:

• TgADF is crucial for the rapid turnover of actin filaments in apicomplexan parasites.
• TgADF plays a vital role in regulating actin dynamics essential for gliding motility and host cell invasion.
• Parasite actin stability is actively controlled by proteins like TgADF, not solely due to intrinsic instability.